The strength properties of S-200E beryllium and 6Al-4V titanium were determined under conditions of combined stress, elevated temperatures and high strain rates. Beryllium specimens were obtained from both extruded rod and hot- pressed block. The range of test conditions included strain rates from 0.001 to 1000/sec, temperatures from 70 to 1000F, and both uniaxial and biaxial states of stress. The biaxial stress states were obtained with thin-walled tubular specimens loaded with axial tension or compression, torsion, or internal pressure. The data presented include the stress-strain curves, yield and failure surfaces in stress space, and the surfaces for total strain to failure. The latter indicates the relative ductility achieved with different applied stress ratios. The effect of temperature and of strain rate on the size and shape of the yield and failure surfaces is determined. In most cases the experimental data correlate well with known yield and failure criteria.